1. Field of the Invention
The present invention relates to a head rail for roller shade, and more particularly to a head rail having an adjustable length.
2. Description of the Related Art
Roller shades are common window coverings to provide privacy and regulate sunlight. A conventional roller shade has a flexible shade fabric windingly received on a head rail for raising and lowering the shade fabric by rotating the head rail. As such roller shade is quite structurally simple, people tend to purchase necessary parts to assemble a roller shade based on their own customized demand. To meet that particular demand, one critical consideration in choosing the assembling elements is that the length of the head rail must correspond to the width of the window to which the roller shade is to be mounted.
To facilitate the cutting of the head rail, the head rail is normally paper-made. Besides requiring an additional machine for cutting, another drawback of the paper-made head rail is that the head rail is often deflected at the center and when the head rail is long it inevitably cannot maintain its straightness due to the weight of the shade fabric. Such a drawback results in a crooked roller shade being unsightly, falling short in its blocking function, and subject to collapse. Moreover, a head rail that is not cut in accordance with the exact mounting condition is irrecoverable and fails the entire mounting of a roller shade.